The aim of the Signaling, Motility and TEM Assays Core is to provide methodology, experimental evaluation, analysis and interpretation of in vitro assays in order to assess the individual behavior of tumor and stromal cells as well as their interactions. The Core performs assays examining 2D motile cell behavior, 3D invasion, and transendothelial migration. These assays permit a complete evaluation of cell behavior during chemotaxis, invasion and migration across a vascular endothelium, and provide a thorough analysis of the invasive capabilities of a given cell type prior to costly and time-consuming animal studies. Moreover, these in vitro assays support and complement the in vivo studies provided by the Multiphoton Imaging, Invasive and TEM Competent Cell Collection and Analysis Core (Core A). Core B also functions as a programmatic resource for the use of unique protein biosensors and for assays examining invadopod formation, and thus ensures that the application of these technologies is uniform across all of the projects. The assays supported by the Core will permit an acute analysis of the molecular mechanisms used by tumor and stromal cells to promote tumor cell invasion, intravasation and extravasation. RELEVANCE (See instructions): Services provided by Core B are essential for the overall objectives of the Program Project to define the detailed interactions between tumor and stromal cells that support invasion and metastasis. These in vitro assays provide information about cellular behavior and mechanism that is essential for the interpretation of in vivo and intravital imaging studies. The Core also coordinates the use of unique biochemical reagents, biosensors and methodologies developed by individual laboratories for distribution to all of the projects.